Y khoa - Dược - Chapter 28: The lymphatic and immune systems

28The Lymphatic and Immune SystemsLearning Outcomes (cont.)28.1 Describe the pathways and organs of the lymphatic system. 28.2 Compare the nonspecific and specific body defense mechanisms. 28.3 Explain how antibodies fight infection. Learning Outcomes (cont.)28.4 Describe the four different types of acquired immunities. 28.5 Describe the causes, signs and symptoms, and treatments of major immune disorders. Introduction Immune system Protects againstBacteria Viruses Fungi Toxins Parasites CancerLymphatic systemWorks with the immune systemOrgansThymusSpleenLymph nodesThe Lymphatic SystemNetwork of connecting vessels Functions to Collect lymph from between cells Collect lipids from digestive organs Defend the body against pathogensLymphatic PathwaysLymphatic capillariesCollect fluidDeliver lymph to lymphatic vesselsLymph vessels – lymph to nodesLymph nodes Remove pathogensStart immune responseLymph SystemLymphatic Pathways (cont.)Efferent lymphatic vessels lymphatic trunksLymphatic collecting ductsThoracic ductRight lymphatic duct Empty into blood streamLymph SystemThe Lymphatic SystemBackThe Lymphatic System (cont.)Area Drained by right lymphatic ductRight lymphatic ductLymph nodesLymphatic trunksLymphatic vesselsLeft internal jugular veinThoracic ductLeft subclavian veinThoracic ductCisterna chyliTissue Fluid and LymphInterstitial fluidFluid in spaces between cells High in nutrients, oxygen, and small proteinsFluid not picked up by cells  lymph Lymph moves bySqueezing action of skeletal musclesSqueezing action of breathingLymph NodesSmall, glandular structuresAfferent lymphatic vessels ~ lymph to nodeEfferent lymphatic vessels ~ lymph from nodeLymph Nodes (cont.)Lymph pools in the nodesCells in nodesMacrophages ~ digest unwanted pathogensLymphocytes ~ start an immune response against pathogenNodes can generate some lymphocytesLymph Nodes (cont.)BackThe Thymus and SpleenThymus Soft, bi-lobed organ located in the mediastinumFunctions Same as lymph nodesAlso produces lymphocytesProduces thymosin – stimulates production of lymphocytesThe Thymus and Spleen (cont.)SpleenLargest lymphatic organUpper left quadrant of abdominal cavityFunctionsFilters blood similarly to lymph nodesRemoves worn-out red cellsApply Your KnowledgeWhat are the lymphatic collecting ducts and what area do they drain?ANSWER: The collecting ducts are: Thoracic duct, which drains the left side of the head and neck, left arm, left side of thorax, entire abdominopelvic area, and both legs; and the right lymphatic duct, which drains the right side of the head and neck, right arm, and right side of the chest.Correct!Defenses Against DiseaseInfection – presence of a pathogen in or on the bodyPathogen – disease-causing agentInnate immunity – nonspecific defenses Immunities – specific defensesNon-Specific DefensesSpecies resistanceMechanical barriersSkinMucous membranesChemical barriersPhagocytosis – phagocytes surround and destroy pathogens and unwanted debris Non-Specific DefensesFever Stimulates removal of iron from bloodActivates phagocytic cellsInflammationRednessHeatSwelling Pain Specific DefensesImmunities Antigens Foreign substances in the bodyOn the surfaces of pathogensHaptens – foreign substances too small to start an immune responseSpecific DefensesAntibodies – respond to specific antigensComplements – work with antibodiesWBCs – lymphocytes and macrophagesSpecific DefensesCytokines – assist in immune response regulationMonokinesIncrease B cell production Stimulate WBC productionSpecific Defenses (cont.)Two major types of lymphocytesBoth recognize antigens in the bodyDiagramT CELLSCell-mediated responseSecrete LymphokinesB CELLSAntibody-mediated responsePlasma cellsMemory B cellsT Cells and B CellsBackSpecific Defenses (cont.)T cell activationMacrophage ingests and digests a pathogen with antigens on itAntigens are placed on the macrophage cell membrane next to a major histocompatibility complex (MHC) T cell binds to the antigen and MHC DiagramSpecific Defenses (cont.)Cytotoxic T cells Memory T cellsHelper T cellsIncrease antibody formationMemory cell formationB cell formationPhagocytosisSpecific Disease (cont.)Natural killer (NK) cellsType of lymphocytePrimarily target cancer cellsKill on contactDo not recognize a specific antigenApply Your KnowledgeIdentify whether each item refers to T cells, B cells, or NK cells:___ Primarily target cancer cells___ Respond to antigens by becoming plasma cells___ Must be activated to respond to an antigen___ Bind to antigens on cells and attack them directly___ Kill on contact___ Need macrophages and MHC for activation___ Make antibodies against specific antigenBNKTTTBNKANSWER:AntibodiesImmunoglobulinsIgA – prevents pathogens from entering bodyIgD – thought to control B cell activityIgE – involved in triggering allergic reactionsAntibodies (cont.)IgGRecognizes bacteria, viruses, and toxinsActivates complementsIgM Binds to antigens on food, bacteria, or incompatible blood cellsActivates complimentsAntibodies (cont.)ActionsAllow phagocytes to recognize and destroy antigensCause antigens to clump togetherCover the toxic portions of antigensActivate complementsApply Your KnowledgeWhat are the possible actions that occur when antibodies bind to antigens?ANSWER: Possible actions include: They allow phagocytes to recognize and destroy  antigens. They make antigens clump together, causing them to be  destroyed by macrophages. They cover the toxic portions of antigens to make them harmless. They activate complements. Immune Responses and Acquired ImmunitiesPrimary immune responseSlow processMemory cells are formedSecondary immune responseQuick and carried out by memory cellsUsually prevents person from developing disease from the antigenImmune Responses and Acquired Immunities (cont.)Naturally acquired active immunityNatural exposure to antigen Makes antibodies and memory cellsArtificially acquired active immunityInjected with pathogen Makes antibodies and memory cellsImmune Responses and Acquired Immunities (cont.)Naturally acquired passive immunityAcquired from motherShort-livedArtificially acquired passive immunityInjected with antibodies Short-livedApply Your KnowledgeANSWER: Immunization is an artificially acquired immunity . A person develops this immunity by being injected with a pathogen and then making antibodies and memory cells against the pathogen. After you give an immunization to a 2-year-old, her mother asks you why this will work to prevent her from getting a disease. What would you tell her?Good Answer!Major Immune System DisordersCancerUncontrolled growth of abnormal cells CarcinogenSigns/symptoms varyTreatment based on stagingMajor Immune System Disorders (cont.)StageDescription Stage 0Very early cancer. Cancer cells are localized in a few cell layers.Stage ICancer cells have spread to deeper cell layers, or some may have spread to surrounding tissues.Stage IICancer cells have spread to surrounding tissues but are considered contained in the primary cancer site.Major Immune System Disorders (cont.)StageDescription Stage IIICancer cells have spread beyond the primary cancer site to nearby areas.Stage IVCancer cells have spread to other organs of the body.RecurrentCancer cells have reappeared after treatment.Major Immune System Disorders (cont.)AllergiesImmune responses to an allergenIgE antibodiesBind to allergens Stimulate mast cells Allergy shotsAnaphylaxis ~ life threatening allergic responseMajor Immune System Disorders (cont.)Allergies (cont.)Signs/symptoms are based on where exposure occursTreatmentAntihistamines, decongestants Epinephrine for anaphylaxisCommon Diseases and Disorders of the Immune SystemAutoimmune diseaseBody attacks its own antigensExamples SclerodermaRheumatoid arthritisMultiple sclerosisGlomerulonephritisCrohn’s diseaseDiabetes mellitus, type ICommon Diseases and Disorders of the Immune System (cont.)DisorderDescription Acquired immunodeficiency syndrome(AIDS)Development of severe signs and symptoms caused by HIV as it destroys lymphocytes (T cells); leaves immune system weakened and susceptible to other diseasesChronic fatigue syndrome (CFS)Condition of severe tiredness not relieved by rest and not related to other illnessesCommon Immune System Disorders (cont.)DisorderDescription LymphedemaBlockage of lymphatic vessels resulting in tissue swellingMononucleosis“Mono”; highly contagious viral infection spread through saliva of infected personSystemic lupus erythematous (SLE)Autoimmune disorder; produces antibodies that target own cells and tissues; affects women more often than menApply Your KnowledgeMatching:___ Immune response to a substance A. CFS___ Blockage of lymphatic vessels B. SLE___ “Kissing disease” C. Cancer___ “Butterfly” rash on face D. Autoimmune disease E. Lymphedema___ Severe tiredness F. Mononucleosis ___ Uncontrolled growth of G. Allergy abnormal cells___ Body attacks its own antigens GFEDCBAANSWER:Excellent!In Summary28.1 The lymph system is composed of pathways known as lymph vessels. In addition to the lymph vessels, the organs of the lymphatic system include lymph nodes, located throughout the body; the thymus, in the mediastinum; and the spleen, located in the LUQ. 28.2 Nonspecific body defenses include species resistance, mechanical and chemical barriers, phagocytosis, fever, and inflammation. Specific defenses are immunities or defenses against very specific antigens created by B cells, T cells, and natural killer (NK) cells.In Summary (cont.)28.3 Antibodies work in the following ways: phagocytosis, antigen clumping, covering (inactivating) toxic portions of antigens, and activating complements. Antibodies are also known as immunoglobulins. IgA prevents pathogens from entering the body; IgD controls B cell activity; IgE works with IgA in triggering allergic reactions; IgG recognizes bacteria, viruses, and toxins and activates complements; and IgM binds to antigens on food, bacteria, or incompatible blood cells. IgM also activates complements. In Summary (cont.)28.4 The four types of immune response are naturally acquired active immunity, such as when someone becomes ill and develops immunity; artificially acquired active immunity, as when an injection is given against a pathogen, preventing illness; naturally acquired passive immunity, which occurs when an infant has its mother’s immunity for a short while after birth and through breast milk; and artificially acquired passive immunity, which occurs after injection of antibodies such as with an antivenom. In Summary (cont.)28.5 Diseases and disorders of the immune system include HIV infection, AIDS, cancer, and allergies, as well as other autoimmune diseases, in which the body attacks its own antigens. The signs, symptoms and treatments are as numerous and varied as the diseases. Some of the more common diseases and disorders are discussed in the Common Diseases and Disorders of the Immune System section near the end of this chapter. End of Chapter 28Thought is an infection. In the case of certain thoughts, it becomes an epidemic. ~Wallace Stevens